The present invention relates to integrated circuit devices having high and low voltage components and techniques for fabricating such devices.
There continues to be a demand for more densely populated and faster integrated circuit devices. To meet these demands, the “on-chip” integrated circuit structural elements continue to be miniaturized, often including a proportional reduction in the gate oxide thickness of Insulated Gate Field Effect Transistors (IGFETs). As the gate oxide thickness decreases, a proportional reduction in operating voltage typically results.
However, the continued decrease in gate oxide thickness generally causes a corresponding decrease in dielectric breakdown voltage. As a result, the breakdown voltage of low voltage components may be less than the output voltage of available power supplies or the operating voltage of external circuits intended to interface with the low voltage components. If gate breakdown voltage is exceeded, the resulting damage typically degrades device performance and reliability. To address this limitation, it is often desirable to have intervening high voltage components operating on the same integrated circuit chip as these low voltage components. One proposed scheme to provide high and low voltage components on the same chip involves the fabrication of gate oxides in different thicknesses. Unfortunately, this approach is exceedingly complex, often resulting in higher manufacturing costs and lower device reliability.
Thus, there is a need for improved integrated circuit devices having both high and low voltage components. There is also a demand for better techniques to provide such voltage devices.